How to convert ArrayList of custom class to JsonArray in Java?

Question

I am trying to convert ArrayList of custom class to JsonArray. Below is my code. It executes fine but some JsonArray elements come as zeros even though they are numbers in the ArrayList. I have tried to print them out. Like customerOne age in the ArrayList is 35 but it is 0 in the JsonArray. What could be wrong?

    ArrayList<Customer> customerList = CustomerDB.selectAll();     Gson gson = new Gson();      JsonElement element =       gson.toJsonTree(customerList , new TypeToken<List<Customer>>() {}.getType());      JsonArray jsonArray = element.getAsJsonArray(); 

Answer 1

Below code should work for your case.

List<Customer> customerList = CustomerDB.selectAll();  Gson gson = new Gson(); JsonElement element = gson.toJsonTree(customerList, new TypeToken<List<Customer>>() {}.getType());  if (! element.isJsonArray() ) { // fail appropriately     throw new SomeException(); }  JsonArray jsonArray = element.getAsJsonArray(); 

Heck, use List interface to collect values before converting it JSON Tree.

Answer 2

As an additional answer, it can also be made shorter.

List<Customer> customerList = CustomerDB.selectAll();  JsonArray result = (JsonArray) new Gson().toJsonTree(customerList,             new TypeToken<List<Customer>>() {             }.getType());